#include<iostream>
#include<math.h>
using namespace std;
double check(double mid){
	double a=mid*mid*mid+3.14;
	return a;
}
int main(){
	double l=-2,r=-1,mid=-1.5; 
	while(fabs(l-r)>0.0001){
		mid=(l+r)/2.0;
		double a=check(mid);
		if(a==0){
			break;
		}
		else{
			if(a<0){
				l=mid;
			}
			else{
				r=mid;
			}
		}
	}
	cout<<mid;
}
